Estimation of the detectable ux of astrophysical neutrinos at the Pierre Auger observatory by means of horizontal air showers

Several astrophysical models and extensions of the Standard Model of elementary particles predict the exis-tence of important sources of very high energy neutrinos across the universe. The detection of these energetic particles will open a new astronomical window and will constitute a new tool to probe deeply into several thick and energetic regions of the universe which can be hardly studied by using only the electromagnetic radiation. When the Pierre Auger Observatory is completed, it will be able to detect ultrahigh energy astrophysical neu-trinos ( EeV) by observing the air showers of secondary particles induced by the neutrinos in collisions with the atmosphere on their route to the detector. In particular, the observatory will look for those events traveling near the horizontal direction. In this work we calculated the detectable ux of ultrahigh energy muon neutrinos at the Pierre Auger Observatory for several particle physics and astrophysical models. Based on these estimates, we found that, in some scenarios, the diffuse ux of active galactic nuclei and topological defects have the greatest possibility of detection of all the spectra which we analyzed and that the muon neutrinos from the GZK cut off will be very difcult to observe by using the above technique and only muon neutrinos. 1